TermVector用法:相关搜索功能及提高高亮显示性能

转自：http://hi.baidu.com/z57354658/blog/item/b80f524b2c92e1fa82025cbd.html

public class TermVectorTest {

    Analyzer analyzer = new SimpleAnalyzer();
    Directory ramDir = new RAMDirectory();

    public void createRamIndex() throws CorruptIndexException, LockObtainFailedException, IOException{

        IndexWriter writer = new IndexWriter(ramDir,analyzer,IndexWriter.MaxFieldLength.LIMITED);

        Document doc1 = new Document();
        doc1.add(new Field("title","java",Store.YES,Index.ANALYZED));
        doc1.add(new Field("author","callan",Store.YES,Index.ANALYZED));
        doc1.add(new Field("subject","java一门编程语言,用java的人很多，编程语言也不少，但是java最流行",Store.YES,Index.ANALYZED,TermVector.WITH_POSITIONS_OFFSETS));

        Document doc2 = new Document();
        doc2.add(new Field("title","english",Store.YES,Index.ANALYZED));
        doc2.add(new Field("author","wcq",Store.YES,Index.ANALYZED));
        doc2.add(new Field("subject","英语用的人很多",Store.YES,Index.ANALYZED,TermVector.WITH_POSITIONS_OFFSETS));

        Document doc3 = new Document();
        doc3.add(new Field("title","asp",Store.YES,Index.ANALYZED));
        doc3.add(new Field("author","ca",Store.YES,Index.ANALYZED));
        doc3.add(new Field("subject","英语用的人很多",Store.YES,Index.ANALYZED,TermVector.WITH_POSITIONS_OFFSETS));

        writer.addDocument(doc1);
        writer.addDocument(doc2);
        writer.addDocument(doc3);

        writer.optimize();
        writer.close();
    }

    public void search() throws CorruptIndexException, IOException{
        IndexReader reader = IndexReader.open(ramDir);
        IndexSearcher searcher = new IndexSearcher(reader);
        Term term = new Term("title","java");   //在title里查询java词条
        TermQuery query = new TermQuery(term);
        Hits hits = searcher.search(query);
        for (int i = 0; i < hits.length(); i++)
        {
            Document doc = hits.doc(i);
            System.out.println(doc.get("title"));
            System.out.println(doc.get("subject"));
            System.out.println("moreLike search: ");

            morelikeSearch(reader,hits.id(i));
        }
    }

    private void morelikeSearch(IndexReader reader,int id) throws IOException
    {
        //根据这个document的id获取这个field的Term Vector 信息，就是这个field分词之后在这个field里的频率、位置、等信息
        TermFreqVector vector = reader.getTermFreqVector(id, "subject");

        BooleanQuery query = new BooleanQuery();

        for (int i = 0; i < vector.size(); i++)
        {
             TermQuery tq = new TermQuery(new Term("subject",
                        vector.getTerms()[i]));   //获取每个term保存的Token

                 query.add(tq, BooleanClause.Occur.SHOULD);

        }

        IndexSearcher searcher = new IndexSearcher(ramDir);

        Hits hits = searcher.search(query);

        //显示代码，略


    }

//Lucene使用TermVector提高高亮显示性能
    public void highterLightSearch() throws CorruptIndexException, IOException{
        IndexReader reader = IndexReader.open(ramDir);

        IndexSearcher searcher = new IndexSearcher(reader);

        TermQuery query = new TermQuery(new Term("subject","java"));

        Hits hits = searcher.search(query);

        //高亮显示设置
        SimpleHTMLFormatter simpleHTMLFormatter = new SimpleHTMLFormatter("","");

        Highlighter highlighter =new Highlighter(simpleHTMLFormatter,new QueryScorer(query));

         // 这个100是指定关键字字符串的context的长度，你可以自己设定，因为不可能返回整篇正文内容
        highlighter.setTextFragmenter(new SimpleFragmenter(100));

        for(int i = 0; i < hits.length(); i++){

            Document doc = hits.doc(i);

            TermPositionVector termFreqVector = (TermPositionVector)reader.getTermFreqVector(hits.id(i), "subject");

            TermFreqVector vector = reader.getTermFreqVector(hits.id(i), "subject");
            TokenStream tokenStream = TokenSources.getTokenStream(termFreqVector);

            String result = highlighter.getBestFragment(tokenStream, doc.get("subject"));

            System.out.println(doc.get("title"));

            System.out.println(result);

        }


    }

    public static void main(String[] args) throws CorruptIndexException, IOException
    {
        TermVectorTest  t = new TermVectorTest();
        t.createRamIndex();
        t.search();
    }

}